In accordance with improvements in the specifications of sets and the use of a high bandwidth memory, the market for die to die interposers has grown. Currently, silicon is mainly used as a material of an interposer, but development of a glass or organic manner has been conducted in order to increase an area and reduce costs. A connecting portion connecting the interposer to a main board, or the like, of the set, is known as an under bump metallurgy (UBM) layer, and as reliability of the connecting portion is significantly affected by a structure of the UBM layer, the structure of the UBM layer needs to be optimized.
In the interposer according to the related art, a redistribution layer (RDL) is formed, a die is attached to the RDL, a package process of molding the die is performed, a package is separated from a carrier, and the UBM layer is formed on a lower surface of the package in contact with the carrier by processes such as a process of forming vias, an exposing process, a plating process, and the like. However, in this case, it is difficult to perform a process due to warpage in the package. Therefore, a separate carrier needs to further be used, and a dedicated line for a process of forming the UBM layer needs to be built up. In addition, products passing through a package line having a low degree of cleanliness again pass through the exposing process and the plating process having a high degree of cleanliness, and a risk of process quality, a risk of a yield reduction, or the like, thus exists.